Methods and systems for controlling radiation beam characteristics for microlithographic processing

ABSTRACT

Methods and apparatuses for controlling characteristics of radiation directed to a microlithographic workpiece are disclosed. An apparatus in accordance with one embodiment of the invention includes a source of radiation positioned to direct a radiation beam having an amplitude distribution, a phase distribution, and a polarization distribution, toward a workpiece. An adaptive structure can be positioned in a path of the radiation beam and can have a plurality of independently controllable and selectively radiation transmissible elements, each configured to change at least one of the amplitude distribution, the phase distribution and the polarization distribution of the radiation beam. A controller can be operatively coupled to the adaptive structure to direct the elements of the adaptive structure to change from one state to any of a plurality of available other states. Accordingly, the adaptive structure can provide radiation beams having a variety of continuously variable distributions for a variety of radiation beam characteristics.

TECHNICAL FIELD

The present invention relates generally to methods and systems forcontrolling radiation beam characteristics, including phase, polarity,and amplitude distributions, during microlithographic processing.

BACKGROUND

Microelectronic features are typically formed in microfeature workpieces(including semiconductor wafers) by selectively removing material fromthe wafer and filling in the resulting openings with insulative,semiconductive and/or conductive materials. One typical process includesdepositing a layer of radiation-sensitive photoresist material on thewafer, then positioning a patterned mask or reticle over the photoresistlayer, and then exposing the masked photoresist layer to a selectedradiation. The wafer is then exposed to a developer, such as an aqueousbase or a solvent. In one case, the photoresist layer is initiallygenerally soluble in the developer, and the portions of the photoresistlayer exposed to the radiation through patterned openings in the maskchange from being generally soluble to being generally resistant to thedeveloper (e.g., so as to have low solubility). Alternatively, thephotoresist layer can be initially generally insoluble in the developer,and the portions of the photoresist layer exposed to the radiationthrough the openings in the mask become more soluble. In either case,the portions of the photoresist layer that are resistant to thedeveloper remain on the wafer, and the rest of the photoresist layer isremoved by the developer to expose the wafer material below.

The wafer is then subjected to etching or metal deposition processes. Inan etching process, the etchant removes exposed material, but notmaterial protected beneath the remaining portions of the photoresistlayer. Accordingly, the etchant creates a pattern of openings (such asgrooves, channels, or holes) in the wafer material or in materialsdeposited on the wafer. These openings can be filled with insulative,conductive, or semiconductive materials to build layers ofmicroelectronic features on the wafer. The wafer is then singulated toform individual chips, which can be incorporated into a wide variety ofelectronic products, such as computers and other consumer or industrialelectronic devices.

As the size of the microelectronic features formed in the waferdecreases (for example, to reduce the size of the chips placed inelectronic devices), the size of the features formed in the photoresistlayer must also decrease. In some processes, the dimensions (referred toas critical dimensions) of selected features are evaluated as adiagnostic measure to determine whether the dimensions of other featurescomply with manufacturing specifications. Critical dimensions areaccordingly selected to be the most likely to suffer from errorsresulting from any of a number of aspects of the foregoing process. Sucherrors can include errors generated by the radiation source and/or theoptics between the radiation source and the mask. The errors can also begenerated by the mask, by differences between masks, and/or by errors inthe etch process. The critical dimensions can also be affected by errorsin processes occurring prior to or during the exposure/developmentprocess, and/or subsequent to the etching process, including variationsin deposition processes, and/or variations in material removalprocesses, e.g., chemical-mechanical planarization processes.

One general approach to correcting lens aberrations in wafer opticsystems (disclosed in U.S. Pat. No. 5,142,132 to McDonald et al.) is toreflect the incident radiation from a deformable mirror, which can beadjusted to correct for the aberrations in the lens optics. However,correcting lens aberrations will not generally be adequate to addressthe additional factors (described above) that can adversely affectcritical dimensions. Accordingly, another approach to addressing some ofthe foregoing variations and errors is to interpose a gradient filterbetween the radiation source and the mask to spatially adjust theintensity of the radiation striking the wafer. Alternatively, a thinfilm or pellicle can be disposed over the mask to alter the intensity oflight transmitted through the mask. In either case, the filter and/orthe pellicle can account for variations between masks by decreasing theradiation intensity incident on one portion of the mask relative to theradiation intensity incident on another.

One drawback with the foregoing arrangement is that it may be difficultand/or time-consuming to change the gradient filter and/or the pelliclewhen the mask is changed. A further drawback is that the gradient filterand the pellicle cannot account for new errors and/or changes in theerrors introduced into the system as the system ages or otherwisechanges.

Another approach to addressing some of the foregoing drawbacks is toprovide a pixilated, diffractive optical element (DOE) in place of afixed geometry diffractive device. The pixilated DOE typically includesan array of electrically addressable pixels, each of which has an “on”state and a “off” state. Pixels in the on state transmit light andpixels in the off state do not. Accordingly, such DOEs can be repeatedlyreprogrammed to generate new patterns, allowing the user to avoid thecost associated with generating a new diffractive element for each newmicrofeature workpiece design. However, a drawback with this approach isthat toggling the pixels between two binary states may not provideadequate control over the radiation impinging on the microlithographicworkpiece, which can in turn result in sub-standard or otherwiseunacceptable workpieces.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partially schematic view of an apparatus for irradiatingmicrolithographic workpieces in accordance with an embodiment of theinvention.

FIG. 2 is a partially schematic illustration of an adaptive structurefor controlling characteristics of the radiation directed to amicrolithographic workpiece in accordance with an embodiment of theinvention.

FIG. 3 is a partially schematic plan view of a portion of the adaptivestructure shown in FIG. 2.

FIG. 4 is a partially schematic illustration of an arrangement forcontrolling elements of an adaptive structure in accordance with anembodiment of the invention.

FIG. 5 is a partially schematic illustration of an adaptive structurethat includes reflective elements in accordance with another embodimentof the invention.

FIG. 6 is a graph illustrating the distributions of two characteristicsof a radiation beam produced using methods and apparatuses in accordancewith embodiments of the invention.

DETAILED DESCRIPTION

A. Introduction

The present disclosure describes methods and apparatuses for controllingthe characteristics of radiation directed toward a microlithographicworkpiece. The term “microlithographic workpiece” is used throughout toinclude workpieces upon which and/or in which submicron circuits orcomponents, data storage elements or layers, vias or conductive lines,micro-optic features, micromechanical features, and/or microbiologicalfeatures are or can be fabricated using microlithographic techniques. Inany of these embodiments, the workpiece is formed from suitablematerials, including ceramics, and may support layers and/or otherformations of other materials, including but not limited to metals,dielectric materials and photoresists.

An apparatus in accordance with one aspect of the invention includes aworkpiece support having a support surface positioned to carry amicrolithographic workpiece. A source of radiation can be positioned todirect a radiation beam along a radiation path toward the workpiecesupport, with the radiation beam having an amplitude distribution, aphase distribution and a polarization distribution. An adaptivestructure can be positioned in the radiation path and can have aplurality of independently controllable and selectively radiationtransmissible elements, each configured to receive a portion of theradiation beam and change from one state to any of a plurality ofavailable other states to change at least one of the amplitudedistribution, the phase distribution, and the polarization distributionof the radiation beam. A controller can be operatively coupled to theadaptive structure to direct the elements of the adaptive structure tochange from the one state to the one of the plurality of other states.

In a further particular aspect of the invention, the plurality ofavailable other states can include a generally continuous spectrum ofother states. The controller can be electrically coupled to each of theelements and can be configured to apply a variable voltage to eachelement to independently change a state of each element from the onestate to any of the plurality of available other states.

A method in accordance with another aspect of the invention includesdirecting a radiation beam from a radiation source along a radiationpath, with the radiation beam having an amplitude distribution, a phasedistribution and a polarization distribution as a function of locationin a plane generally transverse to the radiation path. The method canfurther include impinging the radiation beam on an adaptive structure,and changing a state of at least a portion of the adaptive structurefrom one state to another state to independently change at least twodistributions. The radiation beam can be directed away from the adaptivestructure along the radiation path to impinge on the microlithographicworkpiece.

In a method in accordance with another aspect of the invention, changinga state of at least a portion of the adaptive structure can includedirecting an electrical signal to at least one of a plurality ofelectrically addressable elements arranged in an array of columns androws. In a further aspect of the invention, the radiation beam can bepassed through a reticle positioned between the adaptive structure andthe microlithographic workpiece.

B. Methods and Apparatuses in Accordance with Embodiments of theInvention

Many specific details of certain embodiments of the invention are setforth in the following description and in FIGS. 1-6 to provide athorough understanding of these embodiments. One skilled in the art,however, will understand that the present invention may have additionalembodiments, and that the invention may be practiced without several ofthe details described below.

FIG. 1 schematically illustrates an apparatus 110 for controllablyirradiating a microlithographic workpiece 160 in accordance with anembodiment of the invention. The apparatus 110 can include a radiationsource 120 that directs an electromagnetic radiation beam 128 along aradiation path 180 toward the microlithographic workpiece 160. Theapparatus 110 can further include an adaptive structure 140 that adjuststhe characteristics of the incoming radiation beam 128. As described ingreater detail below, these characteristics can include the spatialdistribution of amplitude (intensity), phase, and/or polarization acrossthe beam 128. Optionally, the radiation beam 128 can then pass through alens system 123 configured to shape and/or magnify the radiation emittedby the source 120. Optionally, the apparatus 110 can further include adiffractive element 122 to diffuse the radiation, and a light tube 124positioned to generate a plurality of images of the radiation source120. The light tube 124 and/or or a sizing lens 125 can size theradiation beam 128, which can then be directed by a mirror 126 through afocusing lens 127 to a reticle or mask 130 along a reticle radiationpath segment 181 a.

The reticle 130 can include reticle apertures 131 through which theradiation passes to form an image on the microlithographic workpiece160. The radiation can pass through a reduction lens 139 which reducesthe image pattern defined by the reticle to a size corresponding to thesize of the features to be formed on the microlithographic workpiece160. The radiation beam 128 then impinges on a radiation-sensitivematerial 161 (e.g., a photoresist layer) of the microlithographicworkpiece 160 to form an image on the material 161. In one embodiment,the beam 128 impinging on the material 161 can have a generallyrectangular shape with a width of from about 5 mm. to about 8 mm. and alength of about 26 mm. In other embodiments, the beam 128 incident onthe layer 161 can have other shapes and sizes. In one embodiment, theradiation can have a wavelength selected from the following values: 13nanometers, 157 nanometers, 193 nanometers, 248 nanometers and 365nanometers. In other embodiments, the wavelength can have a value below,above or between these values, provided the wavelength is suitable forexposing the material 161 on the microlithographic workpiece 160.

The microlithographic workpiece 160 can be carried by a workpiecesupport 150. In one embodiment (a scanner arrangement), the workpiecesupport 150 moves along a workpiece support path 151, and the reticle130 moves in the opposite direction along a reticle path 132 to scan theimage produced by the reticle 130 across the material 161 while theposition of the radiation beam 128 remains fixed. Accordingly, theworkpiece support 150 can be coupled to a support actuator 154 and thereticle 130 can be coupled to a reticle actuator 137.

As the reticle 130 moves opposite the microlithographic workpiece 160,the radiation source 120 can flash to irradiate successive portions ofthe microlithographic workpiece 160 with corresponding successive imagesproduced by the reticle 130, until an entire field of themicrolithographic workpiece 160 is scanned. In one embodiment, theradiation source 120 can flash at a rate of about 20 cycles during thetime required for the microlithographic workpiece 160 to move by onebeam width (e.g., by from about 5 mm. to about 8 mm.). In otherembodiments, the radiation source 120 can flash at other rates. In oneembodiment, the radiation source 120 can flash at the same ratethroughout the scanning process (assuming the reticle 130 and theworkpiece 150 each move at a constant rate) to uniformly irradiate eachfield. In another embodiment, the radiation source 120 can deliver acontinuous radiation beam 128. In either embodiment, each field caninclude one or more dice or chips, and in other embodiments, each fieldcan include other features.

In another embodiment (a stepper arrangement), the radiation beam 128and the reticle 130 can expose an entire field of the microlithographicworkpiece 160 in one or more flashes, while the reticle 130 and theworkpiece support 150 remain in a fixed transverse position relative tothe radiation path 180. After the field has been exposed, the reticle130 and/or the workpiece support 150 can be moved transverse to theradiation path 180 to align other fields with the radiation beam 128.This process can be repeated until each of the fields of themicrolithographic workpiece 160 is exposed to the radiation beam 128.Suitable scanner and stepper devices are available from ASML ofVeldhoven, The Netherlands; Canon USA, Inc., of Lake Success, N.Y.; andNikon, Inc. of Tokyo, Japan.

In a further aspect of the foregoing embodiments, a controller 170 canbe operatively coupled to the reticle 130 (or the reticle actuator 137)and the workpiece support 150 (or the support actuator 154).Accordingly, the controller 170 can include a processor, microprocessoror other device that can automatically (with or without user input)control and coordinate the relative movement between these elements. Thecontroller 170 can also be coupled to the adaptive structure 140 tocontrol the characteristics of the radiation beam 128, as described ingreater detail below.

FIG. 2 is a partially schematic illustration of an adaptive structure140 configured in accordance with an embodiment of the invention. In oneaspect of this embodiment, the adaptive structure 140 includes anentrance aperture 141 sized and positioned to receive the radiation beam128, and an exit aperture 142 sized and positioned to emit the radiationbeam 128. The adaptive structure 140 further includes one or moreadaptive portions 143 (three are shown schematically in FIG. 2 as afirst adaptive portion 143 a, a second adaptive portion 143 b, and athird adaptive portion 143 c) positioned between the entrance aperture141 and the exit aperture 142. In one embodiment, the adaptive portions143 are spaced apart by gaps 144 filled with index-matching fluid 145 toreduce the likelihood for reflection at the interfaces between theadaptive portions 143 and the gaps 144. In another embodiment, the gaps144 can be eliminated, and the adaptive portions 143 can abut againsteach other.

In either of the foregoing embodiments, each adaptive portion 143 canchange from one state to another to change the distribution of aparticular characteristic of the radiation beam 128. For example, in oneembodiment, the first adaptive portion 143 a can be configured to changean amplitude or intensity distribution of the radiation beam 128. Thesecond adaptive portion 143 b can be configured to change a polaritydistribution of the radiation beam 128, and the third portion 143 c canbe configured to change a phase distribution of the radiation beam 128.In other embodiments, one or more of the adaptive portions 143 a-143 ccan change a different characteristic of the radiation beam 128, and/orthe relative positions of the adaptive portions 143 a-143 c can bechanged. In still further embodiments, one or more of the adaptiveportions 143 a-143 c can be eliminated. In any embodiment that includesmore than one adaptive portion 143, each adaptive portion 143 can beindependently controlled to alter the radiation beam characteristic forwhich that particular adaptive portion 143 is tailored, as described ingreater detail below.

FIG. 3 is a partially schematic illustration of the first portion 143 adescribed above with reference to FIG. 2, viewed in a directiongenerally parallel with the radiation path 180. In one aspect of anembodiment shown in FIG. 3, the first portion 143 a can include aplurality of individually controllable adaptive elements 146 positionedin a generally flat layer. In another aspect of the embodiment, eachadaptive element 146 can have a generally rectilinear shape, e.g., asquare shape. In other embodiments, each adaptive element 146 can haveanother shape, e.g., a hexagonal shape or a circular shape. In a furtheraspect of an embodiment shown in FIG. 2, the adaptive elements 146 canbe arranged in an array 147, for example, a generally rectilinear array147. Accordingly, the adaptive elements 146 can be arranged in rows(e.g., rows R1, R2, R3 . . . ) and columns (e.g., columns C1, C2, C3 . .. ). In other embodiments, the adaptive elements 146 can be arranged inother patterns. In any of these embodiments, each adaptive element 146can receive a portion of the incoming radiation beam 128 (FIG. 2), andcan control a selected characteristic of the radiation beam 128. Forexample, in one embodiment, the first portion 143 a can be configured tochange the amplitude or intensity distribution of the incoming radiationbeam 128. Accordingly, the first portion 143 a can include a spatiallight modulator, such as a model LC-SLM available from BoulderNon-Linear Systems of Lafayette, Colo. or a model LCS2-9 available fromCRL Opto Limited of Dunfirmline, Scotland.

In other embodiments, the first portion 143 a can be configured tomodify a polarization of the incoming light beam 128. Accordingly, thefirst portion 143 a can include a plurality of adaptive elements 146,each of which includes a Faraday rotator, such as a ferro-electricliquid crystal rotator or a nematic liquid crystal rotator availablefrom Boulder Non-Linear Systems of Lafayette, Colo. In still anotherembodiment, the first portion 143 a can be configured to control a phasedistribution of the radiation beam 128, and can accordingly includeadaptive elements 146 made of quartz or other suitable materials. In aparticular embodiment, the first portion 143 a can include an array ofelectro-optic modulators, for example, a parallel aligned nematic liquidcrystal spatial light modulator, available from Hamamatsu Corporation ofBridgewater, N.J. In any of these embodiments, each adaptive element 146can control the characteristic of the radiation beam 128 to have a valueselected from a generally continuous spectrum of available values, asdescribed below with reference to FIG. 4.

FIG. 4 is a partially schematic illustration of the controller 170 andsections of the first and second portions 143 a, 143 b of the adaptivestructure 140, configured in accordance with an embodiment of theinvention. For purposes of illustration, two first adaptive elements 146a (of the first portion 143 a) and two second adaptive elements 146 b(of the second portion 143 b) are depicted in FIG. 4. In one aspect ofthis embodiment, the first adaptive elements 146 a are controlledindependently of the second adaptive elements 146 b. In a further aspectof this embodiment, each first adaptive element 146 a can be controlledindependently of the other first adaptive elements 146 a, and eachsecond adaptive element 146 b can be controlled independently of theother second adaptive elements 146 b. Accordingly, the controller 170can include a first element controller 171 a for each of the firstadaptive elements 146 a, and a second element controller 171 b for eachof the second adaptive elements 146 b.

The element controllers 171 a, 171 b (referred to collectively aselement controllers 171) can be configured not only to control eachadaptive element 146 independently of its neighbors, but can alsoselectively establish the state of each adaptive element 146 from aspectrum of more than two available states. In particular, each elementcontroller 171 can control the corresponding adaptive element 146 notjust between an “off” state and an “on” state, but between an off stateand a variety of on states. For example, when the adaptive element 146is configured to control an intensity of the light beam 128, thecorresponding element controller 171 can vary a transmissivity of theadaptive element 146 over a variety of states between completely open(e.g., fully transmissive) and completely closed (e.g.,non-transmissive). When the adaptive element 146 is configured to varythe polarization of the light beam 128, the corresponding elementcontroller 171 can adjust the state of the adaptive element 146 toproduce any of a variety of polarization values between, for example 0°and 90°. When the adaptive element 146 is configured to control a phaseof the incoming light beam 128, the corresponding element controller 171can adjust the state of the adaptive element 146 to produce a phaseshift (compared with neighboring adaptive elements) having any of avariety of phase shift values along a spectrum of such values, forexample, from −180° to +180°.

In any of the foregoing embodiments, each adaptive element 146 can beelectrically activated to change from one state to another, and eachcorresponding element controller 171 can vary an electrical potentialprovided to the adaptive element 146. Accordingly, each adaptive element146 can include at least one electrical input 148 (two are shown foreach of the adaptive elements 146 shown in FIG. 4). As the voltageapplied across each adaptive element 146 is varied, the correspondingcharacteristic (e.g., amplitude, polarization, or phase) controlled bythat adaptive element 146 is also varied. By selecting the voltageapplied by the element controller 171 to the corresponding adaptiveelement 146 from a spectrum of available voltages, an operator (with orwithout assistance from a computer-based routine) can adjust theradiation beam characteristic controlled by that adaptive element 146 tohave a corresponding value. Adjacent adaptive elements 146 can becontrolled in a generally similar manner to control the overalldistribution of the selected characteristic over the cross-section ofthe radiation beam 128. In other embodiments, the adaptive elements 146can receive other inputs that also produce continuously variable statechanges in the parameters described above. In one embodiment, thecharacteristic controlled by each adaptive element 146 does not vary asa function of time for a given state. Accordingly, the characteristiccan be controlled to have no temporal variation at each state, which canincrease the predictability of the results produced with the adaptivestructure 140.

In one embodiment, the controller 170 can include programmable,computer-readable media (e.g., software routines) configured to receiveinput signals from a user and direct appropriate output signals to theadaptive structure 140. In other embodiments, the controller 170 canhave other arrangements. In any of these embodiments, the controller 170can change the state of the adaptive structure 140 so that the sameadaptive structure 140 can be used to provide radiation beams 128 havinga wide variety of characteristics.

One feature of an embodiment of the apparatus 110 described above withreference to FIGS. 1-4 is that the adaptive structure 140 can providefor more precise control of the amplitude, polarity, and/or phasedistributions of the radiation beam 128 because the controller 170 candirect each of the adaptive elements 146 to take on a state selectedfrom a generally continuous spectrum of available states. This degree ofprecision can improve the quality of the microlithographic workpiece160. For example, by providing a radiation beam 128 having an amplitude,polarization and/or phase distribution that varies continuously from oneregion to another, the integrity of the pattern projected onto thematerial 161 can be improved compared with patterns available viaconventional methods. This technique can also improve the depth of focusof the radiation beam 128 impinging on the radiation sensitive material161, and can reduce the sensitivity of the material 161 to variations inexposure time during subsequent processing steps. The reduction insensitivity to exposure time can be particularly important when thethickness of the radiation sensitive material 161 disposed on themicrolithographic workpiece 160 varies. In such instances, the thick andthin regions of the radiation sensitive material 161 can receive similarexposure times without overexposing thin regions and/or underexposingthick regions.

Another feature of an embodiment of the adaptive structure 140 describedabove with reference to FIGS. 1-4 is that by using the foregoingtechniques the adaptive structure 140 can independently vary two or morecharacteristics of the radiation beam 128. For example, the adaptivestructure 140 can be used to independently vary any two of the amplitudedistribution, the phase distribution, and the polarization distributionof the radiation beam 128, or can independently vary all three of thesedistributions. An advantage of this arrangement is that an operator canhave a greater degree of control over the characteristics of theradiation beam 128 impinging on the radiation sensitive material 161.For example, the operator can control the phase distribution of theradiation beam 128 without imposing unintended changes on thepolarization distribution of the beam 128, and vice versa. Accordingly,this arrangement can be particularly advantageous for applications wherea conventional device might alter one characteristic of the radiationbeam as an uncontrolled byproduct of varying a target characteristic.

FIG. 5 is a graph illustrating distributions of two independentlyvariable parameters of a radiation beam 128 (FIG. 1), controlled inaccordance with an embodiment of the invention. The X and Y axes shownin FIG. 5 define a plane generally transverse to the radiation path 180(FIG. 1), and the vertical axes A and P represent amplitude and phasevalues, respectively. The radiation beam 128 can have an amplitudedistribution 590 with two peaks and a phase distribution 591 with asingle peak. In other embodiments, the amplitude distribution 590 andthe phase distribution 691 can have other, independently controlled,shapes. In still further embodiments, other characteristics of theradiation beam 128 (e.g., the polarization of the beam 128) can also becontrolled independently of the phase distribution 591 and/or theamplitude distribution 590.

In other embodiments, the apparatus 110 described above with referenceto FIG. 1 can include other adaptive structures that also independentlycontrol two or more characteristics of the radiation beam 128. Forexample, in an embodiment shown in FIG. 6, an adaptive structure 640includes multiple reflective adaptive portions 643 (three are shown inFIG. 6 as a first adaptive portion 643 a, a second adaptive portion 643b, and a third adaptive portion 643 c). Each of the adaptive portions643 can include a plurality of reflective elements having an orientationor other attribute that is independently controlled by a controller 670.The adaptive structure 640 can also include a directional mirror 649positioned to align the incoming and outgoing portions of the radiationbeam 128 along a straight line axis. In other embodiments, thedirectional mirror 649 can be eliminated. In any of these embodiments,the adaptive portions 643 can control the amplitude, phase, and/orpolarization distribution of the radiation beam 128. In a particularembodiment, for which one of the adaptive portions 643 controls theamplitude distribution, the adaptive portion 643 can include a structuregenerally similar to that described in pending U.S. patent applicationSer. No. 09/945,316, incorporated herein in its entirety by reference.In other embodiments, such an adaptive portion can have otherarrangements.

From the foregoing, it will be appreciated that specific embodiments ofthe invention have been described herein for purposes of illustration,but that various modifications may be made without deviating from thespirit and scope of the invention. Accordingly, the invention is notlimited except as by the appended claims.

1. An apparatus for controlling characteristics of radiation directed toa microlithographic workpiece, comprising: a workpiece support having asupport surface positioned to carry a microlithographic workpiece; asource of radiation positioned to direct a radiation beam along aradiation path toward the workpiece support, the radiation beam havingan amplitude distribution, a phase distribution and a polarizationdistribution; an adaptive structure positioned in the radiation pathbetween the source of radiation and the workpiece support, the adaptivestructure having a plurality of independently controllable andselectively radiation transmissible elements, each configured to receivea portion of the radiation beam and change from one state to any of aplurality of available other states to chance at least one of theamplitude distribution, the phase distribution and the polarizationdistribution of the radiation beam; a reticle disposed between theadaptive structure and the workpiece support; and a controlleroperatively coupled to the adaptive structure to direct the elements ofthe adaptive structure to change from the one state to the one of theplurality of other states.
 2. The apparatus of claim 1 wherein thecontroller is electrically coupled to each of the elements and isconfigured to apply a variable voltage to each element to independentlychange a state of each element from one state to any of a plurality ofavailable other states.
 3. The apparatus of claim 1 wherein the adaptivestructure includes a plurality of Faraday rotator elements, with eachFaraday rotator element coupled to the controller, and wherein thecontroller is configured to independently apply a variable voltage toeach Faraday rotator element to change a state of each Faraday rotatorelement from one state to any of a plurality of available other states,with each Faraday rotator element transmitting radiation at a firstpolarization when in the one state, and transmitting radiation at acorresponding plurality of other polarizations when in any of the otherstates.
 4. The apparatus of claim 1 wherein the adaptive structureincludes a plurality of quartz pixel elements with each pixel elementcoupled to the controller, and wherein the controller is configured toindependently apply a variable voltage to each pixel element to change astate of each pixel element from one state to any of a plurality ofavailable other states, with each pixel element transmitting radiationat a first phase when in the one state, and transmitting radiation at acorresponding plurality of other phases when in any of the other states.5. The apparatus of claim 1 wherein the elements of the adaptivestructure have a non-time varying transmissibility in each of thestates.
 6. The apparatus of claim 1, further comprising a reticledisposed between the adaptive structure and the workpiece support, atleast one of the reticle and the workpiece support being movablerelative to the other.
 7. The apparatus of claim 1 wherein the adaptivestructure includes first, second and third arrays of electricallyaddressable elements, each array intersecting the radiation path andextending in two orthogonal directions generally normal to the radiationpath, the elements of the first array being configured to receive firstelectrical signals to change state and alter the amplitude distributionof the radiation beam, the elements of the second array being configuredto receive second electrical signals to change state and alter the phasedistribution of the radiation beam, the elements of the third arraybeing configured to receive third electrical signals to change state andalter a polarization distribution of the radiation beam.
 8. Theapparatus of claim 1 wherein the adaptive structure includes a pluralityof electrically addressable elements arranged in an array of columns androws.
 9. The apparatus of claim 1 wherein the plurality of availableother states include a generally continuous spectrum of other states.10. An apparatus for controlling characteristics of radiation directedto a microlithographic workpiece, comprising: a workpiece support havinga support surface positioned to carry a microlithographic workpiece; asource of radiation positioned to direct a radiation beam along aradiation path toward the workpiece support, the radiation beam having aphase distribution and a polarization distribution; an adaptivestructure positioned in the radiation path between the source ofradiation and the workpiece support, the adaptive structure having aplurality of independently controllable elements, each configured toreceive a portion of the radiation beam and change from one state to anyof a plurality of available other states to change at least one of thephase distribution and the polarization distribution of the radiationbeam; a reticle disposed between the adaptive structure and theworkpiece support; and a controller operatively coupled to the adaptivestructure to direct the elements of the adaptive structure to changefrom the one state to the one of the plurality of other states.
 11. Theapparatus of claim 10 wherein the adaptive structure is at leastpartially transmissive to the radiation beam to allow at least a portionof the radiation beam to pass through the adaptive structure.
 12. Theapparatus of claim 10 wherein the adaptive structure includes aplurality of reflective elements.
 13. The apparatus of claim 10 whereinthe adaptive structure includes a plurality of Faraday rotator elements,with each Faraday rotator element coupled to the controller, and whereinthe controller is configured to independently apply a variable voltageto each Faraday rotator element to change a state of each Faradayrotator element from one state to any of a plurality of available otherstates, with each Faraday rotator element transmitting radiation at afirst polarization when in the one state, and transmitting radiation ata corresponding plurality of other polarizations when in any of theother states.
 14. The apparatus of claim 10 wherein the adaptivestructure includes a plurality of quartz pixel elements with each pixelelement coupled to the controller, and wherein the controller isconfigured to independently apply a variable voltage to each pixelelement to change a state of each pixel element from one state to any ofa plurality of available other states, with each pixel elementtransmitting radiation at a first phase when in the one state, andtransmitting radiation at a corresponding plurality of other phases whenin any of the other states.
 15. An apparatus for controllingcharacteristics of radiation directed to a microlithographic workpiece,comprising: a workpiece support having a support surface positioned tocarry a microlithographic workpiece; a source of radiation positioned todirect a radiation beam along a radiation path toward the workpiecesupport, the radiation beam having an amplitude distribution, a phasedistribution and a polarization distribution; an adaptive structurepositioned in the radiation path between the source of radiation and theworkpiece support, the adaptive structure being configured to receivethe radiation beam and independently change any two of the amplitudedistribution, the phase distribution and the polarization distributionof the radiation beam; and a reticle disposed between the adaptivestructure and the workpiece support; and a controller operativelycoupled to the adaptive structure to direct the adaptive structure tochange from one state to another state.
 16. The apparatus of claim 15wherein the adaptive structure is configured to change from one state toany of a plurality of available other states to change at least two ofthe amplitude distribution, the phase distribution and the polarizationdistribution.
 17. The apparatus of claim 15 wherein the adaptivestructure includes a plurality of elements, with each element coupled tothe controller, and wherein the controller is configured to apply avariable voltage to each element to independently change a state of eachelement from a first element state to any of a plurality of availablesecond element states.
 18. The apparatus of claim 15 wherein theadaptive structure includes a plurality of Faraday rotator elements,with each Faraday rotator element coupled to the controller, and whereinthe controller is configured to apply a variable voltage to each Faradayrotator element to independently change a state of each Faraday rotatorelement from a first element state to any of a plurality of availablesecond element states, with each Faraday rotator element transmittingradiation at a first polarization when in the first element state, andtransmitting radiation at a corresponding plurality of secondpolarizations when in any of the second element states.
 19. Theapparatus of claim 15 wherein the adaptive structure includes aplurality of quartz pixel elements with each pixel element coupled tothe controller, and wherein the controller is configured to apply avariable voltage to each pixel element to independently change a stateof each pixel element from a first element state to any of a pluralityof available second element states, with each pixel element transmittingradiation at a first phase when in the first element state, andtransmitting radiation at a corresponding plurality of second phaseswhen in any of the second element states.
 20. The apparatus of claim 15,further comprising a reticle disposed between the adaptive structure andthe workpiece support, at least one of the reticle and the workpiecesupport being movable relative to the other.
 21. The apparatus of claim15 wherein the adaptive structure includes at least first and secondarrays of independently electrically addressable elements, each arrayintersecting the radiation path and extending in two orthogonaldirections generally normal to the radiation path, the elements of thefirst array being configured to receive first electrical signals tochange state and alter one of the amplitude distribution, the phasedistribution and the polarization distribution of the radiation beam,the elements of the second array being configured to receive secondelectrical signals to change state and alter another of the amplitudedistribution, the phase distribution and the polarization distributionof the radiation beam.
 22. The apparatus of claim 15 wherein theadaptive structure includes a plurality of electrically addressableelements arranged in an array of columns and rows.
 23. The apparatus ofclaim 15 wherein the adaptive structure includes a plurality of adaptiveelements, each being at least partially transmissive to the radiationbeam to allow at least a portion of the radiation beam to pass through.24. The apparatus of claim 15 wherein the adaptive structure includes aplurality of reflective elements.
 25. An apparatus for controllingcharacteristics of radiation directed to a microlithographic workpiece,comprising: a workpiece support having a support surface positioned tocarry a microlithographic workpiece; a source of radiation positioned todirect a radiation beam along a radiation path toward the workpiecesupport, the radiation beam having an amplitude distribution, a phasedistribution and a polarization distribution in a plane generallytransverse to the radiation path; an adaptive structure positioned inthe radiation path between the source of radiation and the workpiecesupport, the adaptive structure to receive the radiation beam and changefrom one state to any of a plurality of available other states toindependently change each of the amplitude distribution, the phasedistribution and the polarization distribution from a first distributionto a second distribution, with each second distribution selected from agenerally continuous spectrum of second distributions; a controllerelectrically coupled to the adaptive structure to direct electricalsignals to the adaptive structure to change the state of the adaptivestructure; and a reticle positioned between the adaptive structure andthe workpiece support, with at least one of the reticle and theworkpiece support being movable relative to the other.
 26. The apparatusof claim 25 wherein the adaptive structure includes a plurality ofadaptive elements, each being at least partially transmissive to theradiation beam to allow at least a portion of the radiation beam to passthrough.
 27. The apparatus of claim 25 wherein the adaptive structureincludes a plurality of reflective elements.
 28. A method forcontrolling characteristics of radiation directed to a microlithographicworkpiece, comprising: directing a radiation beam from a radiationsource along a radiation path, the radiation beam having an amplitudedistribution, a phase distribution, and a polarization distribution as afunction of location in a plane generally transverse to the radiationpath; impinging the radiation beam on an adaptive structure positionedin the radiation path; changing a state of at least one element of theadaptive structure from one state to any of a plurality of availableother states to change at least one of the amplitude distribution, thephase distribution and the polarization distribution; passing theradiation beam through and away from the at least one element of theadaptive structure; passing the radiation beam through a reticlepositioned between the adaptive structure and the microlithographicworkpiece; and impinging the radiation beam directed away from theadaptive structure on the microlithographic workpiece.
 29. The method ofclaim 28 wherein changing a state includes changing a state to any of aplurality of available other states, all of which correspond todifferent amplitude distributions, or different phase distributions ordifferent polarization distributions.
 30. The method of claim 28,further comprising: passing the radiation beam through first, second andthird arrays of electrically addressable elements, each arrayintersecting the radiation path and extending in two orthogonaldirections generally normal to the radiation path; directing firstelectrical signals to the first array to change a state of the firstarray and alter the amplitude distribution of the radiation beam;directing second electrical signals to the second array to change astate of the second array and alter the phase distribution of theradiation beam; and directing third electrical signals to the thirdarray to change a state of the third array and alter a polarizationdistribution of the radiation beam.
 31. The method of claim 28 whereinchanging a state of at least one element of the adaptive structureincludes directing an electrical signal to at least one of a pluralityof electrically addressable elements arranged in an array of columns androws.
 32. The method of claim 28 wherein changing a state of at leastone element of the adaptive structure includes changing from one stateto any of a plurality of other states in a generally continuous spectrumof other states.
 33. The method of claim 28, further comprising: passingthe radiation beam through a reticle positioned between the adaptivestructure and the microlithographic workpiece; and moving at least oneof the reticle and the microlithographic workpiece relative to the otherwhile impinging the radiation beam on the microlithographic workpiece.34. A method for controlling characteristics of radiation directed to amicrolithographic workpiece, comprising: directing a radiation beam froma radiation source along a radiation path, the radiation beam having aphase distribution and a polarization distribution as a function oflocation in a plane generally transverse to the radiation path;impinging the radiation beam on an adaptive structure positioned in theradiation path; changing a state of at least one element of the adaptivestructure from one state to any of a plurality of available other statesto change at least one of the phase distribution and the polarizationdistribution; directing the radiation beam away from the at least oneelement of the adaptive structure; passing the radiation beam through areticle positioned between the adaptive structure and themicrolithographic workpiece; and impinging the radiation beam directedaway from the adaptive structure on the microlithographic workpiece. 35.The method of claim 34, further comprising passing the radiation beamthrough the at least one element of the adaptive structure.
 36. Themethod of claim 34, further comprising reflecting the radiation beamfrom the at least one element of the adaptive structure.
 37. The methodof claim 34 wherein changing a state includes applying an electricalsignal to the at least one element of the adaptive structure.
 38. Amethod for controlling characteristics of radiation directed to amicrolithographic workpiece, comprising: directing a radiation beam froma radiation source along a radiation path, the radiation beam having anamplitude distribution, a phase distribution, and a polarizationdistribution as a function of location in a plane generally transverseto the radiation path; impinging the radiation beam on an adaptivestructure positioned in the radiation path; changing a state of each ofat least two independently controllable elements of the adaptivestructure from one state to another state to independently change atleast two of the amplitude distribution, the phase distribution and thepolarization distribution; directing the radiation beam away from theadaptive structure along the radiation path; passing the radiation beamthrough a reticle positioned between the adaptive structure and themicrolithographic workpiece; and impinging the radiation beam directedaway from the adaptive structure on the microlithographic workpiece. 39.The method of claim 38 wherein changing a state of each of at least twoindependently controllable elements of the adaptive structure includes:directing one or more first electrical signals to one or more firstelements of the adaptive structure to change one of the amplitudedistribution, the phase distribution and the polarization distribution;directing one or more second electrical signals to one or more secondelements of the adaptive structure to change another of the amplitudedistribution, the phase distribution and the polarization distribution;and passing the radiation beam sequentially through the one or morefirst elements and then through the one or more second elements.
 40. Themethod of claim 38 wherein changing a state includes changing the statefrom one state to any of a plurality of available other states.
 41. Themethod of claim 38, further comprising passing the radiation beamthrough the elements of the adaptive structure.
 42. The method of claim38, further comprising reflecting the radiation beam from the elementsof the adaptive structure.
 43. The method of claim 38, furthercomprising: passing the radiation beam through first, second and thirdarrays of electrically addressable elements, each array intersecting theradiation path and extending in two orthogonal directions generallynormal to the radiation path; directing first electrical signals to thefirst array to change a state of the first array and alter the amplitudedistribution of the radiation beam; directing second electrical signalsto the second array to change a state of the second array and alter thephase distribution of the radiation beam; and directing third electricalsignals to the third array to change a state of the third array andalter a polarization distribution of the radiation beam.
 44. A methodfor controlling characteristics of radiation directed to amicrolithographic workpiece, comprising: directing a radiation beam froma radiation source along a radiation path, the radiation beam having afirst amplitude distribution, a first phase distribution and a firstpolarization distribution as a function of location in a plane generallytransverse to the radiation path; impinging the radiation beam on anadaptive structure positioned in the radiation path; changing a state ofeach of a plurality of adaptive elements of the adaptive structure fromone state to any of a plurality of available other states to change thefirst amplitude distribution to a second amplitude distribution, changethe first phase distribution to a second phase distribution, and changethe first polarization distribution to a second polarizationdistribution, with each change being independent of the other two;directing the radiation beam through and away from the adaptivestructure along the radiation path; passing the radiation beam through areticle positioned between the adaptive structure and themicrolithographic workpiece; and impinging the radiation beam directedaway from the adaptive structure on the microlithographic workpiece. 45.The method of claim 44, further comprising: passing the radiation beamthrough first, second and third arrays of electrically addressableelements, each array intersecting the radiation path and extending intwo orthogonal directions generally normal to the radiation path;directing first electrical signals to the first array to change a stateof the first array and alter the amplitude distribution of the radiationbeam; directing second electrical signals to the second array to changea state of the second array and alter the phase distribution of theradiation beam; and directing third electrical signals to the thirdarray to change a state of the third array and alter a polarizationdistribution of the radiation beam.